1. Field of the Invention
The present invention relates to a fluid saving type fluid feed nozzle, a fluid saving type treatment fluid feed nozzle apparatus, a washing treatment system, and a treatment apparatus used for a wet treatment or a dry treatment such as washing, etching, development or stripping.
2. Description of the Related Art
From the point of view of washing from among the surface fluid treatments of large-sized substrates such as a substrate for solar cell, a substrate for liquid crystal, a substrate for plastic package and the like, the conventional art and problems will be described below.
A washing apparatus shown in FIG. 52 has conventionally been commonly used. FIG. 52A is a side view, and FIG. 52B is a plan view.
Washing is carried out by feeding a washing such as extra-pure water, electrolytic in water, ozone water or hydrogen water by means of a wet treatment liquid feed nozzle 2 onto the upper surface of a substrate 1 while moving the substrate 1, for example, in the arrow A direction.
A washing liquid feed chamber 4, an opening section 6 guiding the washing liquid onto the substrate and a washing liquid introducing port 7 for introducing the washing liquid into the washing liquid feed chamber 4 are formed, as shown in FIG. 53 in this wet treatment liquid feed nozzle 2.
An ultrasonic element 16 is provided above the washing liquid feed chamber 4 to improve washing effect by imparting an ultrasonic wave of the order of MHz band to the washing liquid.
A washing liquid such as extra-pure water, electrolytic ion water, ozone water or hydrogen water is introduced from a washing liquid introducing port 7 into the washing liquid feed chamber 4 and fed to the substrate surface which is an object to be washed through the opening section 6 to wash the same. After washing with the washing liquid, rinsing is performed with a rinsing liquid (extra-pure water in general) by means of a nozzle having a structure similar to that of the wet treatment liquid feed nozzle 2 shown in FIG. 53 with a view to removing the washing liquid from the surface of the object to be washed, and to eliminating residual particles and the like.
However, the aforesaid conventional art has the following problems.
(1) First, it requires a large consumption of a washing liquid or a rinsing liquid.
For example, in order to achieve a cleanliness as represented by a amount of residual particles (for example, Al2O3 particles) remaining on the substrate 1 on a level of 0.5 particles/cm2, when a 500 mm square substrate 1 is washed with a washing liquid such as electrolytic ion water, and then rinsed with a rinsing liquid, the washing liquid and the rinsing liquid must be fed at a flow rate within a range of from about 25 to 30 L/min. The flow rate within a range of from 25 to 30 L/min is selected to permit imparting a stable ultrasonic wave. With a rate of under 25 to 30 L/min, therefore, it becomes impossible to stably impart an ultrasonic wave, and hence to wash cleanly. The consumption of the washing liquid must currently be large for the reason as described above. A liquid consumption of 25 to 30 L/min is still required because the frequency of the ultrasonic wave is raised and the nozzle slit width of ultrasonic washing is reduced. Here is a limit of the existing art.
(2) The second problem is that applicability of ultrasonic wave near the MHz band is limited. There is currently available ultrasonic wave within a range of from 0.7 to 1.5 MHz. In all cases of wet treatment, occurrence of a damage to the object to be treated should be avoided. For this purpose, it is the usual practice to use ultrasonic wave near the MHz band which does not cause a damage resulting from cavitation in washing. A lower limit of usage is adopted from the point of view of avoiding occurrence of a damage to the object to be treated. An upper limit is selected in view of the fact that an effective power available for washing cannot be derived with ultrasonic wave of a frequency of over 2 MHz. Conceivable reasons of impossibility to derive an effective power applicable for washing include the facts that the effective power is low because of a problem in circuit of the ultrasonic element and that, as shown in FIG. 53, the ultrasonic element is distant from the object to be wet-treated, resulting in a large attenuation of ultrasonic power.
(3) The third problem is that, because the washing liquid imparted with an ultrasonic wave as in the washing liquid feed chamber 4 is fed via the narrow opening section 6 onto the object to be washed, there occurs a considerable damping of ultrasonic output, this to the necessity to increase the input power beyond necessity and therefore to a shorter service life of the ultrasonic oscillator. With an ultrasonic wave having a frequency within a range of from 0.7 to 1.5 MHz, while it is possible to derive an effective power applicable for washing, the ultrasonic element is distant from the object to be washed as shown in FIG. 53, and damping of the ultrasonic power is still serious. Load on the adhering surface of the ultrasonic oscillator is very large so that only a slight change in the feed amount of washing liquid or the like may often cause a failure.
(4) The fourth problem lies in cleanliness after washing. Even when a large amount of washing liquid (25 to 30 L/min) is used and a sufficient rinsing is carried out after washing as described above, the resultant cleanliness is limited to a level, resulting in an average cleanliness of about 0.5 particles/cm2.
When a higher cleanliness (about 0.05 particles/cm2) is demanded, the conventional washing technology cannot cope with this demand. Even within a substrate, furthermore, there are fluctuations of cleanliness, and therefore, the portion on the side (b) opposite to the travel of the substrate 1 as shown in FIG. 52 shows a cleanliness lower than that of the portion (a) on the travelling side. As is clear from the distribution of cleanliness shown in FIG. 52B, a problem is that the portion closer to the leading end (a) in the travelling direction has a higher cleanliness, and cleanliness worsens toward the rear end (b) in the travelling direction.
This is attributable to the fact that particles once removed adhere again to the substrate surface while the washing liquid fed from the feed nozzle to the substrate surface flows in the form of a liquid film on the surface of the large-sized substrate to the substrate edge.
The present inventors obtained the following findings regarding washing, a form of wet treatment. Consideration on reasons why a high cleanliness could not be obtained from washing by means of a conventional washing apparatus as shown in FIG. 52b led to a conclusion that it was caused by the following reasons. When the washing liquid is fed from the nozzle opening section 6, the leading end side (a) of the substrate 1 is washed. However, since the substrate 1 travels in the arrow A direction, the washing liquid having washed the surface is transferred smoothly along the surface of the substrate 1 to the rear end (b) of the substrate 1. Because the washing liquid after washing contains particles, these particles adhere again to the surface of the substrate 1 during travel toward the (b) end side. The amount of accumulated particles is larger in the washing liquid after washing at a position closer to the rear end so that the amount of adhesion is larger, leading to a poorer cleanliness.
The present inventors thus clarified that the cause of a poorer cleanliness and an increased consumption of rinsing liquid lay in re-adhesion of once removed particles.
The present invention is therefore to prevent, in a wet treatment method for gradually feeding a wet treatment liquid to an object to be wet-treated, re-adhesion of a wet treatment liquid fed from the wet treatment liquid feed nozzle to the object to be wet-treated, by removing the same from the object to be wet-treated without allowing it to come substantially into contact with portions other than the portion to which the wet treatment liquid has been fed. More particularly, re-adhesion is prevented by immediately removing the wet treatment liquid having contributed to a wet treatment to outside the system.
The present inventors developed a wet treatment liquid feed nozzle, a wet treatment apparatus and a wet treatment method as described above as a technique for preventing re-adhesion.
The invention has therefore an object to pre-liquid-saving type treatment liquid feed nozzle, a treatment liquid feed nozzle apparatus, a washing system and a treatment apparatus which solve the problems of the conventional wet and dry treatment apparatuses and wet and dry treatment methods, permit reduction of the consumption of the treatment liquid to under a tenth the conventional consumption, and allow to obtain a higher cleanliness than the conventional one.
Another object of the invention is to provide a treatment liquid feed nozzle, a treatment liquid feed nozzle apparatus and a treatment apparatus in which leakage of the treatment liquid from the treated surface of the object to be treated to outside is non-existent or very slight, if any.
To solve the foregoing problems, the wet treatment liquid feed nozzle of the invention comprises a nozzle assembly which has an introducing path having an introducing port for introducing a wet treatment liquid at an end thereof, a discharging path having a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system and an opening section opening to an object to be wet-treated provided at a crossing section formed by causing introducing path and the discharging path to cross at the other ends thereof; and pressure control means for controlling a difference between pressure of the wet treatment liquid in contact with the object to be wet-treated and the atmospheric pressure so as to prevent the wet treatment liquid in contact with the object to be wet-treated via the opening section after the wet treatment from flowing to outside the discharging path.
By using this configuration, the treatment liquid comes into contact only with the object to be treated and is therefore effectively utilized. Further, because the treatment liquid after use is immediately removed to outside the system, inconveniences in the treated object caused by the treatment liquid after use can be eliminated.
The wet treatment liquid feed nozzle of the invention may be provided with means for imparting an ultrasonic wave to the wet treatment liquid.
According to this nozzle, it is possible to impart an ultrasonic oscillation via the wet treatment liquid appropriately to the object to be wet-treated, leading, for example in washing, to a remarkable improving effect of cleanliness.
The wet treatment apparatus of the invention comprises at least:
a wet treatment liquid feed nozzle comprising a nozzle assembly which has an introducing path having an introducing port for introducing a wet treatment liquid at an end thereof, a discharging path having a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system and an opening section opening to an object to be wet-treated provided at a crossing section formed by causing the introducing path and the discharging path to cross at the other ends thereof; and pressure control means for controlling a difference between pressure of the wet treatment liquid in contact with the object to be wet-treated and the atmospheric pressure so as to prevent the wet treatment liquid in contact with the object to be wet-treated via the opening section after the wet treatment from flowing to outside the discharging path;
means for causing a relative displacement of the wet treatment liquid feed nozzle and the object to be wet-treated;
a wet treatment liquid feed source; and
means for feeding a wet treatment liquid from the wet treatment liquid feed source to the introducing port of the wet treatment liquid feed nozzle.
According to the wet treatment apparatus invention, it is possible to optimize the relative position of the wet treatment liquid feed nozzle and the object to be wet-treated, and hence to accomplish a wet treatment while easily preventing leakage of the wet treatment liquid and moving throughout the entire surface of the object to be wet-treated.
When moving the wet treatment liquid feed nozzle relatively to the object to be wet-treated, in a structure in which the nozzle assembly and the pressure controller are integrally formed, it suffices to move the integral wet treatment liquid feed nozzle, and in a structure in which a part of the pressure controller is composed, for example, of a large-sized pump, it is not necessary to move the pressure controller, but it suffices to move only the nozzle assembly.
The wet treatment method of the invention comprises the steps of:
gradually feeding a set treatment liquid from a wet treatment liquid feed nozzle to an object to be wet-treated while causing a relative displacement of the object to be wet-treated and the wet treatment liquid feed nozzle, and discharging the wet treatment liquid fed from the wet treatment liquid feed nozzle to the object to be wet-treated without causing the wet treatment liquid to be in contact with portions other than the portion to which the wet treatment liquid has been fed, by controlling a difference between the pressure of the wet treatment liquid in contact with the object to be wet-treated and the atmospheric pressure.
According to the wet treatment liquid feed nozzle of the invention, it is possible to apply wet treatment to the entire surface of even an object to be wet-treated larger in size than the wet treatment liquid feed nozzle by causing a relative displacement of the object to be wet-treated and the wet treatment liquid feed nozzle.
The wet treatment liquid feed nozzle of the invention may be provided with means for imparting an ultrasonic wave to the wet treatment liquid.
According to the wet treatment liquid feed nozzle of the invention, it is possible to effectively apply a wet treatment to an object to be wet-treated by imparting an ultrasonic wave via the wet treatment liquid to the object to be treated.
In the wet treatment liquid feed nozzle of the invention, a portion of a ceiling opposite to the treatment surface of the object to be wet-treated should preferably be formed into a waved shape having a plurality of steps, and a plurality of ultrasonic elements should preferably be provided at an angle to the treatment surface of the object to be wet-treated on the stepped portion.
By using this structure, the gap between the ultrasonic elements and the object to be treated becomes substantially uniform, and it is possible to cause the ultrasonic vibration to act uniformly on the object to be treated.
In the wet treatment liquid feed nozzle of the invention, two introducing paths may be formed to the right and the left of the crossing section, with the discharging path in between.
By using this nozzle, the wet treatment liquid is fed in opposite directions from the right and the left introducing paths, further reducing leakage of the treatment liquid.
In the wet treatment liquid feed nozzle of the invention, two discharging paths may be formed to the right and the left of the crossing section, with the introducing path in between.
By using this nozzle, the wet treatment liquid after use is discharged through the right and the left discharging paths, thus reducing leakage of the treatment liquid.
The wet treatment liquid feed nozzle may be provided with a measuring section capable of measuring the length of the distance to the wet treatment surface of the object to be wet-treated.
With this nozzle, it is possible to accurately determine the distance to the object to be wet-treated, thus ensuring accurate control of the flow of the wet treatment liquid.
Further, another embodiment of the wet treatment liquid feed nozzle of the invention comprises an introducing path having at an end an introducing port for introducing a wet treatment liquid, a discharging path having at an end a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system, a crossing section formed by causing the introducing path and the discharging path to cross at the other ends, and an opening section opening in a mesh shape toward an object to be wet-treated, provided at the crossing section.
According to this wet treatment liquid feed nozzle of the invention, in which the opening has a mesh shape, the wet treatment liquid is prevented from dropping by surface tension of the wet treatment liquid even when the wet treatment liquid feed nozzle is kept away from the object to be wet-treated.
A further embodiment of the wet treatment liquid feed nozzle of the invention comprises an introducing path having at an end an introducing port for introducing a wet treatment liquid, a discharging path having at an end a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system, a crossing section formed by causing the introducing path and the discharging path to cross at the other ends, an opening section opening in a mesh shape toward an object to be wet-treated, provided at the crossing section, and cilia or a film provided around the opening section in parallel with the normal of a treatment surface of the object to be wet-treated.
According to the nozzle of this configuration, leakage of the wet treatment liquid in contact with the treatment surface of the object to be treated to outside the system can be prevented by the cilia or the film.
Another embodiment of the wet treatment liquid feed nozzle of the invention comprises an introducing path having at an end an introducing port for introducing a wet treatment liquid, a discharging path having at an end a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system, a crossing section formed by causing the introducing path and the discharging path to cross at the other ends, an opening section opening in a mesh shape toward an object to be wet-treated, provided at the crossing section, and at least an auxiliary path communicating with the crossing section between the discharging path and the object to be wet-treated on the side of the discharging path.
According to this wet treatment liquid feed nozzle of the invention, when the treatment liquid at the crossing section is in short, it is possible to keep pressure balance between the pressure of the wet treatment liquid and the atmospheric pressure by injecting the treatment liquid by the use of an auxiliary path communicating with the crossing section at which the introducing path and the discharging path cross each other.
Further, another embodiment of the wet treatment liquid feed nozzle of the invention comprises an introducing path having at an end an introducing port for introducing a wet treatment liquid, a discharging path having at an end a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system, a crossing section formed by causing the introducing path and the discharging path to cross at the other ends, an opening section opening in a mesh shape toward an object to be wet-treated, provided at the crossing section, and a parallel flow section permitting flow of the wet treatment liquid provided in parallel with the treatment surface of the object to be wet-treated.
According to this wet treatment liquid feed nozzle of the invention, there occurs no disturbance in the flow of the wet treatment liquid after use and the wet treatment liquid introduced anew from the introducing port, ensuring efficient replenishing.
Another embodiment of the wet treatment liquid feed nozzle of the invention comprises an introducing path having at an end an introducing port for introducing a wet treatment liquid, a discharging path having at an end a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system, a crossing section formed by causing the introducing path and the discharging path to cross at the other ends, an opening section opening toward an object to be wet-treated, provided at the crossing section, and an outer surface of the periphery of the opening section made parallel to the treatment surface of the object to be wet-treated.
According to this wet treatment liquid feed nozzle of the invention, there is available a wide contact surface between the wet treatment liquid and the object to be wet-treated, thus leading to a higher treatment efficiency.
Further, another embodiment of the wet treatment liquid feed nozzle of the invention comprises an introducing path having at an end an introducing port for introducing a wet treatment liquid, a discharging path having at an end a discharging port for discharging the wet treatment liquid after a wet treatment to outside the wet treatment system, a crossing section formed by causing the introducing path and the discharging path to cross at the other ends, an opening section opening in a mesh shape toward an object to be wet-treated, provided at the crossing section, and a sealing member for sealing the crossing section from outside provided on a peripheral edge of the opening section, in a state in contact with the object to be wet-treated or with a support for supporting the object to be wet-treated.
According to this wet treatment liquid feed nozzle of the invention, it is possible to seal the portion to be treated of the object to be treated from outside, thus permitting complete prevention of leakage of the liquid.
A wet treatment apparatus of the invention comprises at least a wet treatment liquid feed nozzle or a wet treatment liquid feed nozzle apparatus of any of the aforesaid embodiments; means for causing a relative displacement of the wet treatment liquid feed nozzle or the wet treatment liquid feed nozzle apparatus; a wet treatment liquid feed source; and means for feeding from the wet treatment liquid feed source to the introducing port of the wet treatment liquid feed nozzle.
According to this wet treatment apparatus, it is possible to appropriately treat the entire surface to be treated of the object to be treated larger in size than the nozzle or the nozzle apparatus by causing a relative displacement of the nozzle or the nozzle apparatus of any of the aforesaid embodiments, to optimize the distance between the nozzle or the nozzle apparatus and the object to be treated, and to appropriately keep the wet treatment liquid.
A further embodiment of the fluid treatment apparatus of the invention comprises a fluid treating path for bringing fluid introduced from an opening and returning the treating fluid to the opening; an introducing path for introducing the treating fluid to the fluid treating path; and a discharging path for discharging the treating fluid brought back from the fluid treating path into the opening.
According to the fluid treatment apparatus of the invention, the consumption of the treating fluid can be reduced to under a tenth the conventional consumption of the same.
The scope of this treatment covers washing with a liquid, etching, polishing, electroless plating, coating, development and stripping of resist of an object to be treated, patterning of a thin film, and analysis of a surface deposit. In other words, the fluid treatment apparatus of the invention is applicable for a washing apparatus, an etching apparatus, a polishing apparatus, an electroless plating apparatus, an apparatus for coating, developing and stripping of resist, a thin film patterning apparatus, and an analyzer.
To apply in a washing apparatus, an etching apparatus, a polishing apparatus, a plating apparatus, or a resist coating apparatus, it suffices to feed a washing liquid, an etching liquid, a polishing liquid, a plating liquid, or a resist stripping liquid, respectively, to a fluid treating path as a treating fluid.
To use as a resist coating apparatus, it suffices to feed a fluid resist as a treating fluid to the fluid treating path, and in order to harden the resist, it suffices to irradiate a light onto the resist by providing light irradiating means as described later (infrared-ray irradiating means, for example).
To achieve a developing apparatus, it suffices to provide, for example, laser irradiating means as light irradiating means, and to irradiate a laser onto the resist through a pattern mask.
A thin film patterning apparatus may be achieved by opening the resist, and then feed a CVD gas to the fluid treating path. For optical CVD, it suffices to provide light irradiating means.
In the case of an analyzer, it suffices to feed a high-purity (for example, an impurity concentration of a few ppt) inert gas to the fluid treating path, incorporate substances to be measured on the object to be treated into the gas, and feed the incorporated gas from the discharging path into an external analyzer to analyze the kinds and the number of elements to be measured.
When using for any of the aforesaid applications, it is convenient to build the fluid treatment apparatus as follows. After bringing a treating build introduced from the opening into contact with the object to be treated, a fluid treating path for bringing the treating fluid back to the opening, an introducing path for introducing the treating fluid to the fluid treating path, and a discharging path for discharging the treating fluid brought back from the fluid treating path into the opening are provided, and light irradiating means for irradiating a light onto the treating fluid is provided in the fluid treating path.
According to the fluid treatment apparatus of the invention, it is possible to reduce the consumption of the treating fluid to under a tenth the conventional consumption, and to improve the light irradiation efficiency.
When using the fluid treatment apparatus of the invention, in order to bring the treating liquid back to the opening after bringing the treating fluid introduced from the opening into contact with the object to be treated, it suffices to appropriately adjust the diameter of the opening, the distance between the object to be treated and the opening, and the pressure of the treating fluid, and to previously determine these values for each fluid treatment apparatus.
For further simplification, it suffices to provide pressure control means for bringing the treating fluid back to the opening of the fluid treating path by controlling the difference between the pressure of the treating fluid in contact with the object to be treated and the atmospheric pressure.
Any of a visible light and a non-visible light may be used as a light. For example, ultraviolet rays, infrared rays, or a laser beam (such as excimer laser beam) are used appropriately in response to the purpose of treatment of the object to be treated.
When the light irradiating means is detachably provided in the fluid treating path, it is possible to impart general-purpose property because of the applicability as a washing apparatus provided with an ultrasonic element having a high washing efficiency by detaching the light irradiating means and attaching the ultrasonic element, thus providing an economic merit.
The washing treatment system of the invention comprises a gas treating path for bringing a treating gas introduced from an opening and returning the treating as to the opening; an introducing path for introducing the treating as to the gas treating path; a discharging path for discharging the treating gas brought back from the gas treating path into the opening; and light irradiating means for irradiating a light onto the treating gas in the gas treating path; the gas treating apparatus communicating with a washing treatment apparatus for washing the object to be treated having been treated in the gas treating apparatus.
As a washing treatment apparatus, it is desirable to use a washing treatment apparatus comprising a washing treating path for bringing a treating liquid introduced from an opening and returning the treating liquid to the opening; an introducing path for introducing the treating liquid to the washing treating path; and a discharging path for discharging the treating liquid brought back from the washing treating path into the opening.
It is needless to mention that this washing treatment apparatus should preferably be provided with pressure control means bringing the washing liquid back to the opening of the washing treating path by controlling the difference between the pressure of the washing liquid in contact with the object to be treated and the atmospheric pressure.
Further, in the invention, the light is irradiated at a higher irradiating efficiency by irradiating the light by the light irradiating means onto the treating fluid, thereby improving the ozone producing efficiency and the sterilizing rate in the treating fluid.
In the invention, the distance between the light irradiating means and the object to be treated is far shorter than in the conventional art. It is therefore possible to feed ozone to the object to be treated before exhaustion of the life of ozone, thus leading to an efficient treatment of the object to be treated. In the fluid treatment apparatus of the invention, the opening area of the opening may be variable.
For example, in a semiconductor wafer, the diameter of the object to be treated may vary. In this case, feeding the treatment fluid always in a constant rate, in spite of the variation in diameter requiring a varied amount of treatment fluid from the opening to the object to be treated would be a waste of the treatment fluid. By making the opening area variable in response to the diameter of the object to be treated, therefore, the amount of feed of the treatment fluid can be reduced for a smaller diameter, contributing to further reduction of the consumption of the treatment fluid. In order to make the opening area variable, it suffices to provide a movable cover onto the opening.
In the fluid treatment apparatus of the invention, a liquid sump should preferably be provided around the opening.
When such a liquid sump is provided around the opening, the treatment fluid after treatment is collected uniformly into the liquid sump from the portions surrounding the opening, not flowing through the discharging path alone, and is discharged from the liquid sump. As a result, the flow of the treatment fluid becomes uniform, permitting uniform treatment of the object to be treated.
Because the treatment fluid in the fluid treating path, which may leak to outside the fluid treatment apparatus, is once collected in the liquid sump, it is possible to prevent the fluid from leaking to outside.
Provision of fine grooves causing capillary action in the liquid sump is more effective for preventing leakage of the treatment liquid to outside since the treatment fluid collected in the liquid sump is sucked up in the fine grooves by the capillary action.
Further, in the fluid treatment apparatus of the invention, the fluid treating path and the discharging path should preferably communicate with each other via the liquid sump.
When treating the object to be treated by means of the treatment fluid, bubbles may be produced in the treatment fluid. For example, the treatment fluid reacts with the object to be treated or a substance adhering to, or formed on, the surface thereof, generating a gas as a reaction product.
As the treatment fluid has the discharging path as the only exit, the generated gas has no escape and remains contained in the treatment fluid. The gas, if present in the treatment liquid, adheres to the surface of the object to be treated and causes a delay in the progress of the essential reaction between the treatment fluid and the surface of the object to be treated, thus leading, for example, to a poorer washing efficiency of the object to be treated. This makes pressure control in the fluid treating path difficult. Further, when imparting an ultrasonic wave to the treatment liquid still containing the gas in an amount exceeding the necessity, cavitation causes the ultrasonic wave to show a considerable damping, causing a decrease in the power serving to remove particles, thus making it impossible to achieve a sufficient washing effect.
In the invention, in contrast, there is provided a pressure adjusting port for positional adjustment of the gas-liquid interface communicating with the fluid treating path. By adjusting the pressure at the pressure adjusting port, therefore, it is possible to form a gas phase and a liquid phase in the fluid treating path. As a result, the gas produced by the treatment of the object to be treated is transferred from the liquid phase to the gas phase, and is as required discharged from the gas phase through the pressure adjusting port to outside. This permits control of the amount of gas present in the treatment fluid, thus making it possible to derive necessary and sufficient cavitation effect.
When imparting an ultrasonic wave, the gas-liquid interface between the gas and liquid phases forms an oscillation free interface, resulting in a more remarkable cavitation effect, thus assisting achievement of an improved washing effect.
By appropriately adjusting the pressure at the pressure adjusting port, it is possible to arbitrarily adjust the ratio of the gas phase to the liquid phase. By ensuring that the gas phase does not communicate directly with the discharging path, the gas does not flow into the discharging path, but is discharged exclusively through the pressure adjusting port. The pressure adjusting port should preferably be provided at the ceiling of the fluid treatment apparatus.
On the other hand, the treatment liquid after the treatment is collected in the liquid sump provided around the opening, and is discharged through the discharging path. When the liquid sum communicates with the discharging path through capillary fine grooves, the treatment liquid collected in the liquid sump after the treatment is sucked up into the discharging path under the effect of capillary phenomenon, without dropping from the liquid sump.
In the invention, the treatment fluid is not limited to any particularly form, but may be a gas a liquid, a gas-liquid mixture, any of various suspensions, or a paste.
According to the fluid treatment apparatus of the invention, the consumption of the treatment fluid can be reduced to under a tenth the conventional consumption, thus permitting improvement of the light irradiating efficiency.
According to the washing treatment system of the invention, the consumption of the treatment fluid can be reduced to under a tenth the conventional one, thus permitting achievement of a higher degree of treatment.